The invention would be better understood if theoretical concepts would be explained in some detail. A hologram is a medium containing information and is nothing more than a high contrast, very fine grain, black and white photographic film. There are several different types of holograms and discussion of each type will be separately addressed below.
The first type is a transmission hologram. In order to playback a hologram, the hologram's reference beam must be shone back through the hologram at the same angle relationship as it had in construction. This where the term transmission hologram arises. Transmission merely means that the reference beam must be transmitted through the hologram in order for the image to be reconstructed. A part of the original beam goes through a glass and a part is reflected at the same angle as its incident. This allows one to bring in the reference beam from an infinite number of angles in relation to the object directed beam, thus, avoiding an inconvenience in playback of having to look directly in the reference beam as with the in-line, transmission hologram.
A transmission type hologram means that the reference beam must be transmitted through the hologram, in order to decode the interference patterns and render the reconstructed image. The light which is used for playback must be coherent or semi-coherent or the image will not be sharp. If a non-coherent source, such as a light from a common, unfiltered slide projector is used, then the hologram will diffract different wavelengths. The interference pattern or grating etched in the emulsion is not particular as to which wavelengths it bends or focuses; therefore, an unclear overlapping spectrum of colors resembling the object is produced.
A hologram will playback just as well with laser light of a different color or wavelength than the light with which it was made. However, the object will appear to be of a different size and/or distance from the plate. For example, a hologram of an object made with neon or red light will playback that object smaller or seemingly further away if a blue color laser is used. This is because the grating will bend the blue or shorter light less severely than the red with which it was made and with which it is meant to be decoded.
Another type of a hologram is plane or volume hologram. In a plane transmission hologram, the reference beam is hitting the film from the same side as the object beam. In a volume reflection hologram, the reference beam makes an arc clear around so that it hits the film from the opposite side as the modulated object beam.
The hologram can be viewed in white light or light which contains many different wavelengths. The one requisite is that the light be from a point source and be a somewhat straight line, such as a slide projector light or penlight, or the sun on a clear day. The reflection hologram can do this because in a way it acts as its own filter. In a reflection hologram the fringes are packed so closely together that they constitute layers throughout the thickness of the emulsion. The spacing between fringes remains constant. If a distance between a first fringe and a second fringe is two microns, for example, then the distance between the remaining layers of fringes will also be two microns. This distance is a function of the wavelength of light used in constructing the hologram and also the angle difference between reference and object beams. This layered affair allows the reflection hologram to absorb, or not reflect, any of the colors or wavelengths of light which are not the correct length. The wavelength which matches the fringe spacing will be reflected: the crests of the wavelengths which are too short or too long will eventually miss one of the planes and be absorbed into the darkness of the emulsion. In a reflection type hologram, the playback light or reconstruction beam comes from the same side of the hologram as the viewer. Some parts of the incident light are reflected, some are not, depending on the interference pattern. If the hologram was made correctly the result should be a visible three-dimensional image. In the transmission type hologram, the reconstruction beam must pass through the hologram and come towards the viewer from the opposite side of the hologram while in the reflection type the playback source comes from the same side of the hologram as the viewer.
Another type of a hologram is a multiplex hologram. This type of a hologram has a more common usage in today's technology. The multiplex hologram is the holographic storage of photographic information. In the first stage a series of photographs or a certain amount of motion picture footage of the subject is exposed. The number of stills or frames taken depends on how much of an angle of view of the subject is desired in the finished hologram. For example, if a 360-degree view of the subject, exposure of three frames per degree of movement around the subject is recommended (usually the camera remains stationary and the subject rotates) this will result in the exposure of 1080 frames. The film must be developed and using a laser, a series of “slit” holograms using each frame of film as a subject for each slit of holographic film must be made. The slits are usually about one millimeter wide and are packed so closely that there is no “dead space” in between. Also, the hologram is bleached so that the strips disappear. Usually a multiplex hologram yields a horizontal not a vertical parallax. This is because the camera usually moves around (or the subject moves around in front of the camera) and does not usually pass over the subject. Also, psychologically, horizontal parallax is much more desirable and the lack of horizontal parallax is much more noticeable than the lack of vertical parallax. The multiplex hologram is usually, though not always, made on flexible film coated with the same holographic emulsion as the plates. The procedure can be totally mechanical so that a machine can expose a slit hologram per each frame of footage at a very rapid pace. The advantage of this type of hologram is that it is possible to have a hologram of almost anything captured on an ordinary film without a need of an expensive, clumsy procedure. The disadvantage is that it is not truly a hologram but photographic information holographically stored.
There are several U.S. patents available, however, none of them fulfill the particular need that the present invention addresses. For example, U.S. Pat. No. 6,031,519 to O'Brien teaches a holographic direct manipulation interface comprising an apparatus for displaying a hologram, detection sensors of any movement relative to the hologram and a processing means for covering a location of a detected object directly relative to its position on the displayed hologram into an output signal.
A graphical user interface (GUI) is a type of computer application user interface that allows people to interact with a computer and computer-controlled devices. A GUI typically employs graphical icons, visual indicators or special graphical elements, along with text, labels or text navigation to represent the information and actions available to a user. The actions are usually performed through direct manipulation of the graphical elements.
Holographic images can be created as single or consecutive images using available holographic technology. These technologies include mirrors, lasers, light and images strategically positioned to cause the proper reflection to yield a holographic image broadcast through an entry point in the laser and mirror positioning system. Black background and rooms with low or no light may enhance the appearance of the holographic image or images, which may also use a holographic plate as a display medium. Holographic systems may be large in size and spread out over a large broadcasting area or may be compact enough to fit in spaces smaller than a desk top. Holographic technology is only limited in size by the size of the component parts. By using holographic technology, images may be displayed multi-dimensionally rather simply on a planar projection.
Currently, progress has been made in technologies that can enhance the capability and range of holographic media in projects that employ multi-million mirror systems and via companies that have designed specialized high speed and high capacity microprocessors for specialized jobs, other than holographic systems, where the technology could be applied to holographic technologies to make possible the proper positioning of millions of mirrors at a rate of between 24 to 60 or more frames of video per second, with corresponding synched audio.
Holographic displays generated over the last 20-year period utilize various configurations including lasers with images on glass plates such as an AGFA 8E75HD glass plate or other glass plates as well a laser such as a Spectra Physics 124B HeNe laser, a 35 mW laser diode system utilizing different processing methods such as pyrochrome processing. Split beam techniques can also use Multi H1 to Multi H2. Such configurations as 8×10, triethanolomine, from Linotronic 300 image setter film are also commonly utilized or a configuration with rear-illuminated for 30×40 cm reflection hologram, where a logo floats 18-inches in front of the plate.